JP2007274298A - Multiplate digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiplate digital camera using a multicolor prism such as a tricolor prism and a plurality of solid-state imaging elements which can reduce a required value for positional accuracy for fixing the multicolor prism and the solid-state imaging elements, and can be remarkably reduced in manufacturing cost. <P>SOLUTION: The multicolor digital camera comprises the multicolor prism 3 which separates the light from a subject into a plurality of colors and outputs them; the plurality of solid-state imaging elements 41-43 arranged on the output side of the multicolor prism for outputting a plurality of colors, respectively; a position correction information storage 8 which stores position correction information for correcting the deviation of a photographed image due to position mismatching of the solid-state imaging elements; and a synthesizing portion 7 which corrects the positions of image informations from the solid-state imaging elements, based on the position correction information and synthesizes them. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-plate digital camera that takes an image by imaging a plurality of color lights branched by a multi-color separation prism on a plurality of solid-state image sensors, and more specifically, fixes the multi-color separation prism and the solid-state image sensor. The present invention relates to a multi-plate digital camera that can reduce the required value of position accuracy and can greatly reduce the manufacturing cost.

  Digital cameras that can shoot images such as moving images and still images at high resolution and output the obtained image information as digital information have become widespread. Among them, three-plate digital cameras are used for applications that require highly accurate color information. A three-plate type digital camera is a digital camera that takes an image by forming images of three-color light separated by a three-color separation prism on three solid-state image sensors (CCD, etc.). Since the band of the three-color light is selected by a uniform color filter (mirror), highly accurate color information can be acquired.

  For this reason, a three-plate digital camera is advantageous for obtaining color information accurately. An example of such an application is a medical camera. Accurate colors can be reproduced with high-accuracy color information, and slight color changes such as living tissue can be accurately expressed.

To manufacture a three-plate digital camera, it is necessary to position and fix (adhere) the three-color separation prism and the three solid-state imaging elements with high accuracy. As such a technique, a technique described in Patent Document 1 below is known. Patent Document 1 describes an adjustment assembly method for positioning and fixing a three-color separation prism and three solid-state imaging elements with high accuracy.
Japanese Patent Laid-Open No. 2003-232907

  Recently, the resolution of digital cameras has been increasing rapidly, and the pitch between pixels of a solid-state image sensor has also been miniaturized. Therefore, it is necessary to align each pixel with high accuracy. For example, if the inter-pixel pitch of a CCD as a solid-state image sensor is 5 μm, it must be aligned and fixed with a deviation within 1/2 of the minimum.

  The alignment of the solid-state imaging device has three degrees of freedom, that is, the position in the X and Y directions and the angle of the coordinate axis for one solid-state imaging device. It is necessary to adjust 6 degrees of freedom to align the other two positions based on one of the solid-state imaging devices. The adjustment requires highly skilled technology, and requires manual adjustment by skilled technicians. Also, an adjustment device needs to be highly accurate and expensive. For this reason, the prism unit composed of the three-color separation prism and the solid-state imaging device has a high manufacturing cost and is not suitable for mass production.

  In order to obtain a high-resolution and high-quality camera, it is necessary to further increase the accuracy of alignment of the solid-state imaging device. If a high-resolution solid-state imaging device is used, the pixel pitch is further reduced, and the required alignment accuracy is further severed. As described above, since the manufacturing cost of the prism unit is increased, there is a problem in that the manufacturing cost of the entire high resolution three-plate camera is also increased.

  Therefore, the present invention is a multi-plate digital camera using a multi-color separation prism such as a three-color separation prism and a plurality of solid-state image sensors, and requires a positional accuracy for fixing the multi-color separation prism and the solid-state image sensor. An object of the present invention is to provide a multi-plate digital camera capable of reducing the value and significantly reducing the manufacturing cost.

  In order to achieve the above object, a multi-plate digital camera of the present invention is arranged on a multi-color separation prism that separates and outputs light from a subject into a plurality of colors, and a multi-color separation prism on the output side of the plurality of colors. A plurality of solid-state image pickup devices, a position correction information storage unit for storing position correction information for correcting a shift of a captured image due to a position mismatch of the solid-state image pickup device, and image information from the solid-state image pickup device. And a combining unit that performs position correction based on the position correction information and combines them.

  Further, in the above multi-plate digital camera, the combining unit calculates a coordinate value in another solid-state image sensor from the coordinate value in one of the solid-state image sensors and the position correction information, and corrects the position. Preferably there is.

  In the multi-plate digital camera described above, it is preferable that the combining unit obtains image information with coordinate values corrected in position in another solid-state imaging device by interpolation calculation.

  In the multi-plate digital camera, the position correction information is preferably information related to an angle between coordinates and an offset amount.

  Further, in the above multi-plate digital camera, the multi-color separation prism is arranged so that the light from the subject is separated into three colors and outputted, and the three-color separation prism is provided with the three solid-state imaging devices. can do.

  Since this invention is comprised as mentioned above, there exist the following effects.

  Even if the position of the solid-state image sensor for each color fixed to the multi-color separation prism is not precisely aligned, it is possible to position digital images of multiple colors by using position correction information indicating the positional relationship between them. Correct and combine correctly. Thereby, the required value of the positional accuracy for fixing the multicolor separation prism and the solid-state imaging device can be reduced, and the manufacturing cost can be greatly reduced.

  Since the synthesizing unit calculates the coordinate value in the other solid-state image sensor from the coordinate value and the position correction information in one of the solid-state image sensors, the position correction and the image synthesis are performed in a short time by performing the coordinate calculation at high speed. Can be processed.

  Since the combining unit obtains the image information with the coordinate value corrected for the position in the other solid-state imaging device by interpolation calculation, it is possible to obtain high-accuracy image information and to perform high-quality image composition.

  Since the position correction information is information related to the angle between coordinates and the offset amount, the correction calculation of the coordinate value can be performed at high speed by a primary calculation.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of a multi-plate digital camera 1 of the present invention. This is an example of using a three-color separation prism as a multi-color separation prism to form a three-plate digital camera. The light from the subject at the time of photographing enters the three-color separation prism 3 through the lens 2 and is separated and branched into three-color light of green, blue, and red by the three-color separation prism 3. An image is formed on each solid-state imaging device. As the three solid-state imaging devices, a green light CCD 41, a blue light CCD 42, and a red light CCD 43 are fixed to the three-color separation prism 3 by bonding or the like.

  FIG. 2 is an enlarged view showing the arrangement of the three-color separation prism 3 and the CCDs 41 to 43. As shown in the figure, the three-color separation prism 3 has a first prism 31, a second prism 32, and a third prism 33 fixed to each other by bonding or the like. A dichroic mirror that reflects green light and transmits light in other wavelength bands is provided at the boundary surface between the first prism 31 and the second prism 32. A dichroic mirror that reflects blue light and transmits red light is provided at the boundary surface between the second prism 32 and the third prism 33.

  Further, as shown in the figure, a CCD 41 for green light is fixed to the first prism 31, a CCD 42 for blue light is fixed to the second prism 32, and a CCD 43 for red light is fixed to the third prism 33. Has been. The light from the subject that has passed through the lens 2 is separated into each color by each dichroic mirror as shown in the figure, and forms an image on the CCD for each color.

  Conventionally, it has been necessary to precisely adjust and fix the positional relationship between the three-color separation prism and the CCD for each color. This is because the output of the CCD for each color is simply synthesized to obtain an image signal. If the position of the CCD for each color is shifted, a normal image signal cannot be obtained even if the outputs of the CCDs are simply combined. For this reason, it is necessary to align the three-color separation prism and the CCD for each color with high accuracy, which increases the manufacturing cost of the prism unit.

  The present invention eliminates the need to precisely adjust the positional relationship between the three-color separation prism 3 and the CCDs 41 to 43 for the respective colors, thereby reducing the manufacturing cost of the prism unit. That is, in the present invention, there is a possibility that the positions of the CCDs 41 to 43 for the respective colors are not aligned, and there is a possibility that an image is formed at a different position of each CCD. It is assumed that the focus positions (optical path lengths) when images are formed on the CCDs 41 to 43 are aligned with each CCD. That is, the focus position is aligned in the manufacturing process of the three-color separation prism 3.

  Returning again to the description of FIG. In accordance with the images formed on the CCDs 41 to 43 for the respective colors, image signals of the respective color lights are extracted from the CCDs 41 to 43. Each image signal is amplified by the G amplifier circuit 51, the B amplifier circuit 52, and the R amplifier circuit 53 for each color, further converted into a digital signal by the AD converters 61 to 63, and sent to the synthesizing unit 7. The synthesizing unit 7 synthesizes the input digital image signal after correcting the position, and outputs it as a normal image signal. Position correction information indicating the positional deviation between the CCDs is stored in the position correction information storage unit 8. The synthesizing unit 7 performs position correction of the digital image signal based on the position correction information stored in the position correction information storage unit 8.

  The combining unit 7 does not need to be provided inside the camera body that houses the lens 2 and the three-color separation prism 3. As the synthesizer 7, an image processing apparatus such as a computer may be used. In this case, the camera body and the synthesizer 7 are connected by a cable to perform position correction and synthesize processing. The digital image signal and the position correction information are sent to the combining unit 7 through the cable. Since the position correction information storage unit 8 stores information unique to the camera body, it is preferably provided in the camera body.

  FIG. 3 is a diagram showing the relationship of the coordinates of the CCDs 41 to 43. In each of the CCDs 41 to 43, element-specific coordinates based on the pixel arrangement are set. For example, the coordinates are set so that the center point of each pixel is an integer coordinate position. The unique coordinates of the green light CCD 41 are represented by coordinate axes Xg and Yg, the unique coordinates of the blue light CCD 42 are represented by coordinate axes Xb and Yb, and the red light CCD 43 unique coordinates are represented by coordinate axes Xr and Yr. Yes.

  Here, if the intrinsic coordinates XgYg of the green light CCD 41 are used as a reference, an image located on the coordinates XgYg different from the intrinsic coordinates is formed on the CCDs 42 and 43 as shown in FIG. . The positional shift between the coordinates in the blue light CCD 42 is represented by the angle θb between the coordinate axes and the offset Cb of the origin of the coordinates XgYg. The offset Cb is a vector indicating the point (Pb, Qb) on the intrinsic coordinates XbYb. Here, the point (Pb, Qb) is a coordinate on the unique coordinate XbYb corresponding to the origin of the coordinate XgYg.

  The positional shift between the coordinates in the CCD 43 for red light is represented by the angle θr between the coordinate axes and the offset Cr of the origin of the coordinates XgYg. The offset Cr is a vector indicating a point (Pr, Qr) on the intrinsic coordinates XrYr. Here, the point (Pr, Qr) is a coordinate on the unique coordinate XrYr corresponding to the origin of the coordinate XgYg.

A position corresponding to a point G (xg, yg) on the image of the green light CCD 41 is set to a point B (xb, yb) on the blue light CCD 42 and a point R (xr, y on the red light CCD 43). yr), points B and R can be obtained by the following equation.
B = AbG + Cb Formula 1
R = ArG + Cr Formula 2

  In Equation 1, B is a vector representing the point (xb, yb) on the intrinsic coordinate XbYb, Ab is a matrix corresponding to the coordinate rotation of the angle θb, G is a vector representing the point (xg, yg) at the coordinate XgYg, Cb is a vector indicating a point (Pb, Qb) on the specific coordinate XbYb. In Equation 2, R is a vector representing the point (xr, yr) on the intrinsic coordinate XrYr, Ar is a matrix corresponding to the coordinate rotation of the angle θr, G is a vector representing the point (xg, yg) at the coordinate XgYg, Cr is a vector indicating a point (Pr, Qr) on the intrinsic coordinates XrYr.

  From Formulas 1 and 2, points B and R on the intrinsic coordinates of each CCD corresponding to an arbitrary point G on the green light CCD 41 are obtained. The synthesizing unit 7 obtains corresponding points B and R with respect to the image information of the green light point G by Expressions 1 and 2, and the image information of the point B of the blue light CCD 42 and the CCD 43 for red light. The image information of the point R is synthesized. The synthesizing unit 7 is provided with an image memory for storing image information of each color, and the image information at points B and R is extracted from the image memory.

  Information on the angle θb, the offset Cb, the angle θr, and the offset Cr necessary for the calculations of Expressions 1 and 2 is stored in the position correction information storage unit 8 as position correction information. The position correction information can be obtained by calibrating the multi-plate digital camera 1. That is, it is possible to take a reference image with the multi-plate digital camera 1 and obtain each data of the position correction information from the image position in each CCD. The position correction information obtained by calibration is stored in the position correction information storage unit 8 in advance.

  If the coordinate values of the points B and R become integers, the pixel corresponding to the value can be selected immediately, but generally the coordinate values of the points B and R are not integers. In that case, the most appropriate pixel is selected, or the image information corresponding to the coordinate value is calculated from the image information of surrounding pixels by interpolation or the like. The simplest method is to select a pixel having a center position closest to the coordinate values of the points B and R and use the image information of the pixel.

  In order to obtain image information by interpolation calculation, it is easy to perform interpolation calculation from image information of pixels corresponding to four integer coordinate points (points whose coordinate values are integers) around the points B and R. It is only necessary to perform first-order interpolation calculation with respect to each coordinate axis from the coordinate values of the points B and R to obtain image information corresponding to the points B and R. If either one of the two coordinate values of the point B is an integer, the interpolation calculation can be performed by using two integer coordinate points instead of four integer coordinate points. The same applies to the point R.

  Further, higher-order interpolation calculation is performed using information on pixels of integer coordinate points larger than four (for example, 16 surrounding pixels) to obtain image information corresponding to points B and R with higher accuracy. You can also.

  As described above, even if the positions of the CCDs for the respective colors fixed to the three-color separation prism are not precisely aligned, the three-color digital can be obtained by using the position correction information indicating the positional relationship between them. It is possible to correct the image by correcting the position. Thereby, the required value of the positional accuracy for fixing the three-color separation prism and the CCD can be reduced, and the manufacturing cost can be greatly reduced.

  In the above embodiment, an example of using a three-color separation prism as a multi-color separation prism and a three-plate digital camera has been described. However, as a two-color separation prism or a four-color separation prism, a two-plate or four-plate digital camera is used. It can also be a camera. You may make it decompose | disassemble into five colors or more.

  In addition, the specific coordinates of the green light CCD among the CCDs for the respective colors are used as a reference. Further, although an example has been described in which the three-color separation prism performs color separation into red, green, and blue (RGB), other types of color separation may be performed. Furthermore, although the example which uses CCD as a solid-state image sensor is given, arbitrary solid-state image sensors other than CCD can be used.

  According to the multi-plate digital camera of the present invention, the required value of positional accuracy for fixing the three-color separation prism and the solid-state imaging device can be reduced, and the manufacturing cost can be greatly reduced.

1 is a block diagram showing an overall configuration of a multi-plate digital camera 1 of the present invention. It is an enlarged view showing the arrangement of the three-color separation prism 3 and the CCD. It is a figure which shows the relationship of the coordinate of each CCD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multi-plate type digital camera 2 Lens 3 Three-color separation prism 7 Composition part 8 Position correction information storage part 31 1st prism 32 2nd prism 33 3rd prism 41-43 CCD
51 G amplifier circuit 52 B amplifier circuit 53 R amplifier circuit 61-63 AD converter

Claims (5)

A multi-color separation prism (3) for separating and outputting light from a subject into a plurality of colors;
A plurality of solid-state imaging devices (41 to 43) respectively disposed on the output side of the plurality of colors of the multi-color separation prism (3);
A position correction information storage unit (8) for storing position correction information for correcting a shift of a captured image due to a position mismatch of the solid-state imaging device (41 to 43);
A multi-plate digital camera having a combining unit (7) for correcting the position of image information from the solid-state imaging device (41 to 43) by using the position correction information. The multi-plate digital camera according to claim 1,
The synthesizing unit (7) performs position correction by calculating a coordinate value in another solid-state image sensor from the coordinate value in one of the solid-state image sensors (41 to 43) and the position correction information. Plate type digital camera. The multi-plate digital camera according to claim 2,
The synthesizing unit (7) is a multi-plate digital camera that obtains image information with coordinate values corrected in position in another solid-state imaging device by interpolation calculation. A multi-plate digital camera according to any one of claims 2 and 3,
The position correction information is a multi-plate digital camera that is information about an angle between coordinates and an offset amount. A multi-plate digital camera according to any one of claims 1 to 4,
The multi-color separation prism (3) separates and outputs light from the subject into three colors,
A multi-plate digital camera in which three solid-state image sensors (41 to 43) are arranged on the multi-color separation prism (3).

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